Sensitivity improver for temperature controllers



Sept. 18, 1951 c. A. WEST 2,568,574-

SENSITIVITY IMPROVER FOR TEMPERATURE CONTROLLERS Filed May 26, 1948 1 2 4 K &- 5.

-4. Z s s H 555 I {I j H E :l 7 I 4 ,0 H j u I3 2 INVENTOR Patented Sept. 18, 1951 SENSITIVITY IMPROVER FOR TEMPERA- TURE CONTROLLERS Charles Alfred West, Southbridge, Mass.

Application May 26, 1948, Serial No. 29,288

1 Claim. 1

This invention relates to a mechanism adapted to improve the sensitivity of mechanisms heretofore used for performing a mechanical operation such as opening or closing a valve under the automatic control of a temperature responsive device.

It is the general object of my invention to improve the construction of such mechanisms as heretofore known in such manner as to provide more rapid response, a higher sensitivity and more satisfactory operation.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claim.

A preferred form of the invention is shown in the drawings in which Fig. l is a part sectional side elevation of a controller embodying my sensitivity improver.

Fig. 2 is a sectional plan taken along the general line 2-2 of Fig. 1 showing detail construetion to be described.

Referring to Fig. l of the drawings the actuating mechanism includes a hood 3 having a depending open chassis frame 6 adapted to be mounted on a valve H of any suitable description provided only that the valve may be opened and closed by axial movement of a valve stem 16 slidable in a gland [5 of a stufiing box of a valve I4. A temperature responsive fluid-filled device 13 is connected by a capillary tube 2 and a passage 29 in a hub 52 to a pressure chamber A between a cup 50 and a bellows 5| and hub 52. The varying downward pressure on the cup 50 and the attached operaitng stem 4 due to the varying temperature in the deviceB is opposed by the upward spring pressure of a coil compression spring 1. The valve stem i6 is screwed into a rotatable internally threaded plunger l8 with an integral rectangular boss at its lower end and the valve stem l6 may be secured in axially adjusted position by a locknut ll. The plunger I8 is slidable in a sleeve IS. The sleeve [9 is slidable in a collar 20 screwed into the lower end of the operating stem 4. The upper end of the sleeve I9 is equipped with a tubular nut 22 screwed thereto. The nut 22 is normally held by a spiral compression spring 22a against the upper end of the collar 20 which acts as a stop. The upper end of the spring 22a engages a fixed stop 55. The operating stem 4 is attached to the bellows cup 50 inside the hood 3. The lower end of the operating stem 4 is guided by a collar 2| which is fixed in the lower end 01 a hollow pression spring 1. 8 is a section of one arm of.

the depending chssis frame 6.

12 is a frame cross-bar into a central aperture,

of which the hollow adjusting screw 5 is fixed. The operating stem 4 attached to the bellows cup 50 necessarily travels the same distance as the bellows cup. In the self-acting controllers heretofore used the valve stem also travels the same distance as the operating stem. The added mechanism of my invention now to be described increases the travel of the valve stem I6 so that its travel is very considerably greater than the travel of the operating stem 4 and the bellows cup 50. The rectangular boss at the lower end of the plunger I8 is provided on two opposite sides with horizontal threaded spindles 36'. These two spindles act as pivots for two levers 28 and 25. These two levers are provided at their outer ends with rollers 26 and 34. The two rollers pass with a small working clearance into two rectangular holes 33 and 38 in the two depending arms of the chassis frame 6.

At the lower end of the sleeve I9 is a horizontal rectangular bar 23 integral with it and extending outwards almost to the two depending arms of the chassis frame. Each end of the horizontal bar 23 is provided with a vertical slot which extends from the end almost to the sleeve hole 21 to suit a small wire spindle is drilled and vertically above this in the horizontal bar 23 and equidistant from the axis of the operating stem 4 a similar hole 37 is drilled. A connecting link 24a with corresponding pivot holes is assembled with its pivots. A similar connecting link 24 is inserted and pivoted at corresponding points 21a and 31a on the other lever 25 and the bar 23. If the operating stem 4 moves upwards or downwards the bar 23, the two links 24 and 24a and also the two pivots 21 and 21a will move through the same distance (neglecting any slight difference due to the very small angular motion of the links 24 and 24a).

The level of the two outer ends of the two levers 25 and 28 is kept constant by the two rollers 26 and 34, but the inner ends swivelling on the two spindles 36 move through twice the distance moved through by the operating stem 4. This also applies to the plunger l8 and to the valve stem l6 attached thereto, so that the valve stem travel is twice that of the operating stem 4, or the ratio of the two is 2: 1.

In the lever 28 and half way between the center of the roller 34 and the spindle 36 a small so as to provide slots for the four pivoted members 26, 34, 24 and 24a.

The two levers 25 and 28 swivel on the two spindles 36, the two spindles being provided with nuts and locknuts which are adjusted so as to allow the two levers to swivel freely. The two levers 25 and 28 are shown with bent inner ends to clear the rectangular boss at the lower end of the plunger l8. I6 is a section of the valve stem IE of Fig. l which is screwed into the plunger [8. It-iwill'be seen from Figs. 1 and 2 that my invention enables the sensitivity of the controller tofbe considerably increased and therefore it also.

increases the speed of response and the efiiciency of the controller generally. It also increases the available overall travel of the valve stem without imposing increased and deleterious flexing of the bellows thus favoring a longer life for the bellows, and it also enables the controller to' be used with valves requiring a longer valve stem travel than i otherwise practicable.

. Having thus described my invention and the advantages thereof, I do not wish to be limited to: the details herein described other than as set forth in the claim, and what I claim is: l

The combination of a sensitivity improver and a temperature controlled actuating mechanism for moving, by. means of the said sensitivity improver, the valve stem and valve disc of a valve,

the said mechanism being under the control of a fluid filled device which is responsive to temperature changes, the said mechanism including achassis composed of a cylindrical hood and a depeiiding open frame with two vertical side arms, arranged for assembly to the said valve, the said fluid filled device comprising an expansible fluid pressure container and a bulb connected thereto by a capillary tube,.the said container, tube and bulb being charged with a temperature responsive fluid, the said expansible fluid pressure container including an upper stationary member centered by a spigot to the top of the said hood, the cup or lower movable member of the said container having centrally attached thereto a tubular operating stem, the fluid pressure in the said container varying with the temperature in the said bulb but always tending to move the said cup and the attached operating stem in a downward direction, a heavycompression coil spring mounted so as to always tend to move the said cup of the said expansible fluid pressure container in an upward direction or towards a collapsed position, the resultant upward or downward force of the combination of the said spring and the said expansible fluid pressure containeroperating on the said cup with its tubularoperating stem, the said operating stem being provided with a collar fixed into the interior of its lower end, the said operating stem being operatively connected to the said valve stem by means'of the said sensitivity improver, the said sensitivity improver including a tubular sleeve, freely slidable in the said collar, a hollow tubular nut screwed to the upper end of the said sleeve and acting as a stop, normally pressed by a compression coil spring into contact with the upper end of the said collar, the said tubular sleeve beingprovided at its lower end with a horizontal rectangular bar extending outwards almost to the said two depending arms of the said chassis, a tubular plunger freely slidable inside the said sleeve, the said plunger beingthreaded internally and screwed to the said valve stem, and also provided at its lower end with a rectangular boss which carries on each of two opposite sides a horizontal spindle, two levers swivelling on the said two spindles, the outer ends of the said two levers each carrying a pivoted roller, the said two rollers entering two rectangular holes, one in each of the said two depending arms of the said chassis, the center points of the said' two levers being pivoted to the lower ends of two links, the upper ends of the said two links being pivoted to the said horizontal bar, all thefour pivots at both ends of the said two links being equidistant from the axis of the said operating stem, and also means for altering the positions of the said pivots at theends of the said two links and thus varying the mechanical advantage between the said operating stem and the said valve stem.

CHARLES ALFRED WEST.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS 

